[PATCH v3 6/6] ext4: cleanup legacy buffer_head direct IO code

Matthew Bobrowski
2019-09-12T11:05:11Z

Remove buffer_head direct IO code that is now redundant as a result of
porting across the read/write paths to use iomap infrastructure.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
fs/ext4/ext4.h | 3 -
fs/ext4/extents.c | 11 +-
fs/ext4/file.c | 7 -
fs/ext4/inode.c | 398 +---------------------------------------------
4 files changed, 5 insertions(+), 414 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index bf660aa7a9e0..2ab91815f52d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1555,7 +1555,6 @@ enum {
EXT4_STATE_NO_EXPAND, /* No space for expansion */
EXT4_STATE_DA_ALLOC_CLOSE, /* Alloc DA blks on close */
EXT4_STATE_EXT_MIGRATE, /* Inode is migrating */
- EXT4_STATE_DIO_UNWRITTEN, /* need convert on dio done*/
EXT4_STATE_NEWENTRY, /* File just added to dir */
EXT4_STATE_MAY_INLINE_DATA, /* may have in-inode data */
EXT4_STATE_EXT_PRECACHED, /* extents have been precached */
@@ -2522,8 +2521,6 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
-int ext4_dio_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create);
int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create);
int ext4_walk_page_buffers(handle_t *handle,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 92266a2da7d6..a869e206bd81 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1753,16 +1753,9 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
*/
if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
return 0;
- /*
- * The check for IO to unwritten extent is somewhat racy as we
- * increment i_unwritten / set EXT4_STATE_DIO_UNWRITTEN only after
- * dropping i_data_sem. But reserved blocks should save us in that
- * case.
- */
+
if (ext4_ext_is_unwritten(ex1) &&
- (ext4_test_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN) ||
- atomic_read(&EXT4_I(inode)->i_unwritten) ||
- (ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN)))
+ (ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN))
return 0;
#ifdef AGGRESSIVE_TEST
if (ext1_ee_len >= 4)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 413c7895aa9e..d2ff383a8b9f 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -155,13 +155,6 @@ static int ext4_release_file(struct inode *inode, struct file *filp)
return 0;
}

-static void ext4_unwritten_wait(struct inode *inode)
-{
- wait_queue_head_t *wq = ext4_ioend_wq(inode);
-
- wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
-}
-
/*
* This tests whether the IO in question is block-aligned or not.
* Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f52ad3065236..a4f0749527c7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -826,136 +826,6 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096

-/*
- * Get blocks function for the cases that need to start a transaction -
- * generally difference cases of direct IO and DAX IO. It also handles retries
- * in case of ENOSPC.
- */
-static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int flags)
-{
- int dio_credits;
- handle_t *handle;
- int retries = 0;
- int ret;
-
- /* Trim mapping request to maximum we can map at once for DIO */
- if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
- bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
- dio_credits = ext4_chunk_trans_blocks(inode,
- bh_result->b_size >> inode->i_blkbits);
-retry:
- handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
- if (IS_ERR(handle))
- return PTR_ERR(handle);
-
- ret = _ext4_get_block(inode, iblock, bh_result, flags);
- ext4_journal_stop(handle);
-
- if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
- goto retry;
- return ret;
-}
-
-/* Get block function for DIO reads and writes to inodes without extents */
-int ext4_dio_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh, int create)
-{
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- if (!create)
- return _ext4_get_block(inode, iblock, bh, 0);
- return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
-}
-
-/*
- * Get block function for AIO DIO writes when we create unwritten extent if
- * blocks are not allocated yet. The extent will be converted to written
- * after IO is complete.
- */
-static int ext4_dio_get_block_unwritten_async(struct inode *inode,
- sector_t iblock, struct buffer_head *bh_result, int create)
-{
- int ret;
-
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = ext4_get_block_trans(inode, iblock, bh_result,
- EXT4_GET_BLOCKS_IO_CREATE_EXT);
-
- /*
- * When doing DIO using unwritten extents, we need io_end to convert
- * unwritten extents to written on IO completion. We allocate io_end
- * once we spot unwritten extent and store it in b_private. Generic
- * DIO code keeps b_private set and furthermore passes the value to
- * our completion callback in 'private' argument.
- */
- if (!ret && buffer_unwritten(bh_result)) {
- if (!bh_result->b_private) {
- ext4_io_end_t *io_end;
-
- io_end = ext4_init_io_end(inode, GFP_KERNEL);
- if (!io_end)
- return -ENOMEM;
- bh_result->b_private = io_end;
- ext4_set_io_unwritten_flag(inode, io_end);
- }
- set_buffer_defer_completion(bh_result);
- }
-
- return ret;
-}
-
-/*
- * Get block function for non-AIO DIO writes when we create unwritten extent if
- * blocks are not allocated yet. The extent will be converted to written
- * after IO is complete by ext4_direct_IO_write().
- */
-static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
- sector_t iblock, struct buffer_head *bh_result, int create)
-{
- int ret;
-
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = ext4_get_block_trans(inode, iblock, bh_result,
- EXT4_GET_BLOCKS_IO_CREATE_EXT);
-
- /*
- * Mark inode as having pending DIO writes to unwritten extents.
- * ext4_direct_IO_write() checks this flag and converts extents to
- * written.
- */
- if (!ret && buffer_unwritten(bh_result))
- ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
-
- return ret;
-}
-
-static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
-{
- int ret;
-
- ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
- inode->i_ino, create);
- /* We don't expect handle for direct IO */
- WARN_ON_ONCE(ext4_journal_current_handle());
-
- ret = _ext4_get_block(inode, iblock, bh_result, 0);
- /*
- * Blocks should have been preallocated! ext4_file_write_iter() checks
- * that.
- */
- WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
-
- return ret;
-}
-
-
/*
* `handle' can be NULL if create is zero
*/
@@ -3653,268 +3523,6 @@ const struct iomap_ops ext4_iomap_ops = {
.iomap_end = ext4_iomap_end,
};

-static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
- ssize_t size, void *private)
-{
- ext4_io_end_t *io_end = private;
-
- /* if not async direct IO just return */
- if (!io_end)
- return 0;
-
- ext_debug("ext4_end_io_dio(): io_end 0x%p "
- "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
- io_end, io_end->inode->i_ino, iocb, offset, size);
-
- /*
- * Error during AIO DIO. We cannot convert unwritten extents as the
- * data was not written. Just clear the unwritten flag and drop io_end.
- */
- if (size <= 0) {
- ext4_clear_io_unwritten_flag(io_end);
- size = 0;
- }
- io_end->offset = offset;
- io_end->size = size;
- ext4_put_io_end(io_end);
-
- return 0;
-}
-
-/*
- * Handling of direct IO writes.
- *
- * For ext4 extent files, ext4 will do direct-io write even to holes,
- * preallocated extents, and those write extend the file, no need to
- * fall back to buffered IO.
- *
- * For holes, we fallocate those blocks, mark them as unwritten
- * If those blocks were preallocated, we mark sure they are split, but
- * still keep the range to write as unwritten.
- *
- * The unwritten extents will be converted to written when DIO is completed.
- * For async direct IO, since the IO may still pending when return, we
- * set up an end_io call back function, which will do the conversion
- * when async direct IO completed.
- *
- * If the O_DIRECT write will extend the file then add this inode to the
- * orphan list. So recovery will truncate it back to the original size
- * if the machine crashes during the write.
- *
- */
-static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- struct ext4_inode_info *ei = EXT4_I(inode);
- ssize_t ret;
- loff_t offset = iocb->ki_pos;
- size_t count = iov_iter_count(iter);
- int overwrite = 0;
- get_block_t *get_block_func = NULL;
- int dio_flags = 0;
- loff_t final_size = offset + count;
- int orphan = 0;
- handle_t *handle;
-
- if (final_size > inode->i_size || final_size > ei->i_disksize) {
- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto out;
- }
- ret = ext4_orphan_add(handle, inode);
- if (ret) {
- ext4_journal_stop(handle);
- goto out;
- }
- orphan = 1;
- ext4_update_i_disksize(inode, inode->i_size);
- ext4_journal_stop(handle);
- }
-
- BUG_ON(iocb->private == NULL);
-
- /*
- * Make all waiters for direct IO properly wait also for extent
- * conversion. This also disallows race between truncate() and
- * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
- */
- inode_dio_begin(inode);
-
- /* If we do a overwrite dio, i_mutex locking can be released */
- overwrite = *((int *)iocb->private);
-
- if (overwrite)
- inode_unlock(inode);
-
- /*
- * For extent mapped files we could direct write to holes and fallocate.
- *
- * Allocated blocks to fill the hole are marked as unwritten to prevent
- * parallel buffered read to expose the stale data before DIO complete
- * the data IO.
- *
- * As to previously fallocated extents, ext4 get_block will just simply
- * mark the buffer mapped but still keep the extents unwritten.
- *
- * For non AIO case, we will convert those unwritten extents to written
- * after return back from blockdev_direct_IO. That way we save us from
- * allocating io_end structure and also the overhead of offloading
- * the extent convertion to a workqueue.
- *
- * For async DIO, the conversion needs to be deferred when the
- * IO is completed. The ext4 end_io callback function will be
- * called to take care of the conversion work. Here for async
- * case, we allocate an io_end structure to hook to the iocb.
- */
- iocb->private = NULL;
- if (overwrite)
- get_block_func = ext4_dio_get_block_overwrite;
- else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
- round_down(offset, i_blocksize(inode)) >= inode->i_size) {
- get_block_func = ext4_dio_get_block;
- dio_flags = DIO_LOCKING | DIO_SKIP_HOLES;
- } else if (is_sync_kiocb(iocb)) {
- get_block_func = ext4_dio_get_block_unwritten_sync;
- dio_flags = DIO_LOCKING;
- } else {
- get_block_func = ext4_dio_get_block_unwritten_async;
- dio_flags = DIO_LOCKING;
- }
- ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
- get_block_func, ext4_end_io_dio, NULL,
- dio_flags);
-
- if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
- EXT4_STATE_DIO_UNWRITTEN)) {
- int err;
- /*
- * for non AIO case, since the IO is already
- * completed, we could do the conversion right here
- */
- err = ext4_convert_unwritten_extents(NULL, inode,
- offset, ret);
- if (err < 0)
- ret = err;
- ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
- }
-
- inode_dio_end(inode);
- /* take i_mutex locking again if we do a ovewrite dio */
- if (overwrite)
- inode_lock(inode);
-
- if (ret < 0 && final_size > inode->i_size)
- ext4_truncate_failed_write(inode);
-
- /* Handle extending of i_size after direct IO write */
- if (orphan) {
- int err;
-
- /* Credits for sb + inode write */
- handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
- if (IS_ERR(handle)) {
- /*
- * We wrote the data but cannot extend
- * i_size. Bail out. In async io case, we do
- * not return error here because we have
- * already submmitted the corresponding
- * bio. Returning error here makes the caller
- * think that this IO is done and failed
- * resulting in race with bio's completion
- * handler.
- */
- if (!ret)
- ret = PTR_ERR(handle);
- if (inode->i_nlink)
- ext4_orphan_del(NULL, inode);
-
- goto out;
- }
- if (inode->i_nlink)
- ext4_orphan_del(handle, inode);
- if (ret > 0) {
- loff_t end = offset + ret;
- if (end > inode->i_size || end > ei->i_disksize) {
- ext4_update_i_disksize(inode, end);
- if (end > inode->i_size)
- i_size_write(inode, end);
- /*
- * We're going to return a positive `ret'
- * here due to non-zero-length I/O, so there's
- * no way of reporting error returns from
- * ext4_mark_inode_dirty() to userspace. So
- * ignore it.
- */
- ext4_mark_inode_dirty(handle, inode);
- }
- }
- err = ext4_journal_stop(handle);
- if (ret == 0)
- ret = err;
- }
-out:
- return ret;
-}
-
-static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
-{
- struct address_space *mapping = iocb->ki_filp->f_mapping;
- struct inode *inode = mapping->host;
- size_t count = iov_iter_count(iter);
- ssize_t ret;
-
- /*
- * Shared inode_lock is enough for us - it protects against concurrent
- * writes & truncates and since we take care of writing back page cache,
- * we are protected against page writeback as well.
- */
- inode_lock_shared(inode);
- ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
- iocb->ki_pos + count - 1);
- if (ret)
- goto out_unlock;
- ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
- iter, ext4_dio_get_block, NULL, NULL, 0);
-out_unlock:
- inode_unlock_shared(inode);
- return ret;
-}
-
-static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- size_t count = iov_iter_count(iter);
- loff_t offset = iocb->ki_pos;
- ssize_t ret;
-
-#ifdef CONFIG_FS_ENCRYPTION
- if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
- return 0;
-#endif
-
- /*
- * If we are doing data journalling we don't support O_DIRECT
- */
- if (ext4_should_journal_data(inode))
- return 0;
-
- /* Let buffer I/O handle the inline data case. */
- if (ext4_has_inline_data(inode))
- return 0;
-
- trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
- if (iov_iter_rw(iter) == READ)
- ret = ext4_direct_IO_read(iocb, iter);
- else
- ret = ext4_direct_IO_write(iocb, iter);
- trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret);
- return ret;
-}
-
/*
* Pages can be marked dirty completely asynchronously from ext4's journalling
* activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do
@@ -3952,7 +3560,7 @@ static const struct address_space_operations ext4_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
@@ -3969,7 +3577,7 @@ static const struct address_space_operations ext4_journalled_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_journalled_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
};
@@ -3985,7 +3593,7 @@ static const struct address_space_operations ext4_da_aops = {
.bmap = ext4_bmap,
.invalidatepage = ext4_da_invalidatepage,
.releasepage = ext4_releasepage,
- .direct_IO = ext4_direct_IO,
+ .direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
--
2.20.1